Date: October 2020
What is gravity? In 1666 Sir Isaac Newton first mathematically described the force of gravity, creating Newton’s laws of universal gravitation. Another scientist you may have heard of, Albert Einstein, later added to Newton’s ideas about gravity with his theory of relativity. Albert Einstein developed the theory of relativity, a scientific explanation about how space relates to time. Special relativity says that motion is always relative and that space and time exist in relation to each other. His ideas about gravity were inspired by him watching an apple fall from a tree. Newton wondered what force made the apple fall downward instead of simply floating away. Gravity is a force of attraction that pulls together all matter (anything you can physically touch). The more matter something has, the greater the force of its gravity. That means really big objects have a stronger gravitational pull. The gravitational pull of an object depends on how massive it is and how close it is to the other object. For example, the Sun has much more gravity than Earth (because it is far bigger in size), but we stay on Earth’s surface instead of being pulled to the Sun because we are much closer to Earth. In addition Gravity is the force that keeps the Earth and other planets in orbit around the Sun. Weight is actually the measurement of the force of gravity pulling on an object. You would weigh more or less on other planets, depending on if those planets have more or less gravity than Earth. Since gravity is related to mass, you would weigh less on smaller planets and weigh more on larger planets. Which also means you would be weightless in space since there is no gravitational pull. High and low tides in the ocean are caused by the moon’s gravity.
Let's say two objects of different weights but they are the same size are dropped from the same height, they would both hit the ground at the same time. The force of gravity will make them travel at the same speed. In physics, weight is described as a force and can also be measured in Newtons. They named the unit of measurement off the scientist who discovered the concept of gravity, Sir Isaac Newton. Click the link below to learn more https://www.pbs.org/video/gravity-m3swlv/ Watch the video below for a quick summary